Substitute loading containers at Zeebrugge (6)
I believe the answer is:
ersatz
'substitute' is the definition.
(synonyms)
'loading containers at zeebrugge' is the wordplay.
'loading' says the answer is hidden in the clue (the solution is part of the clue's 'load').
'ERSATZ' is hidden within 'containers at zeebrugge'.
(Other definitions for ersatz that I've seen before include "Spurious" , "Cheap substitute or imitation" , "Made in imitation, from German" , "Artificial or inferior imitation" , "Bogus" .)